This invention relates to magnetic heading simulators and, more particularly, to a fully automated magnetic heading reference simulator for use with aircraft navigation systems.
A necessary part of any instrumentation in an aircraft in order to navigate that aircraft is a compass. Most aircraft contain compasses which are of the magnetic type utilizing the magnetic field of the earth to determine the heading of the aircraft. In normal flight conditions the compass is slaved to the magnetic heading as determined by a flux valve sensitive to the earth's magnetic field. The flux valve in many aircraft is located in the wing tip. Some compasses can be unslaved from the magnetic heading and slaved to the directional gyros present in the aircraft navigation system. In this case, the gyros can be used to drive the compass to any heading desired in the case of testing and maintenance regardless of the actual heading of the airplane. However, on many aircraft the compass cannot be unslaved from the flux valve and, therefore, up until the present time the heading reference system had to be tested at whatever the actual heading of the aircraft was when it was parked at the test facility.
Testing of the heading system in a static condition at a single heading is undesirable since it really does not check the system under dynamic conditions and problems which are present during the dynamic change from one heading to another or at certain headings other than the one at which the tests were conducted might not be detected during testing at a single fixed heading. Consideration has been given to developing equipment which would provide a simulated magnetic field which could then be placed in the vicinity of the flux valve of the aircraft and varied to develop magnetic fields simulating many different and changing headings for test purposes. However, the location of the flux valve in the wing of the aircraft makes the development and use of such equipment impractical.
It is therefore an object of the present invention to provide apparatus for simulating magnetic heading for purposes of test and evaluation of the heading reference system.
It is an object of this invention to provide such a magnetic heading simulation that utilizes as much as possible of the existing circuitry of the aircraft so that the system can be tested from end-to-end rather than piecemeal.
It is a further object of this invention to provide a heading simulator which can be operated under programmed computer control so that headings and heading rates can be fed into the system automatically.